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W. DRALLE March 17, 1964 MACHINE FOR GRINDING WORKPIECES HAVING FACING SURFACES 6 Sheets-Sheet 1 Filed Jan. 10, 1962 March 17, 1964 w. DRALLE 3,124,907

MACHINE FOR GRINDING WORKPIECES HAVING FACING SURFACES \Filed Jan. 10, 1962 e Sheets-Sheet 2 /(//j N //X/ A. L N

i v I H H INVENTOR.

W. DRALLE March 17, 1964 6 Sheets-Sheet 3 Filed Jan. 10, 1962 H \N V U W -m H TN w y m 4. 0 WW 7 v w w N\ &\L\\

llullulll-lll'i'lllnl'll March 17, 1964 w. DRALLE 3,124,907

MACHINE FOR GRINDING WORKPIECES HAVING FACING SURFACES Filed Jan, 10, 1962 6 Sheets-Sheet 4 Mae/m 3% E- J All/s.

March 17, 1964 w. DRALLE 3,124,907

MACHINE FOR GRINDING WORKPIECES HAVING FACING SURFACES Filed Jan. 10, 1962 6 Sheets-Sheet 5 IN V EN TOR.

17' W/vzvt March 17, 1964 w. DRALLE 3,124,907

MACHINE FOR GRINDING WORKPIECES HAVING FACING SURFACES Filed Jan. 10, 1962 6 Sh ts-Sheet 6 INVENTOR. G

United States Patent Fitted Ian. 10, 1962, ser. N0. 165,339 isv Claims. (CI. 51-46) This invention relates to grinding machines, and more particularly to machines for simultaneously grinding a plurality of surfaces on a single workpiece.

It is an object of the present invention to provide a novel and improved grinding: machine capable of simultaneously grinding a number of workpiece surfaces, and which is especially adapted for grinding one or more pairs of oppositely disposed surfaces in a rapid and continuous manner, and with a constant finish distance between thesurfaces despite successive dressing of the wheels.

It is another object to provide an improved grinding machine of this type which permits feed movement between the workpiece and grinding wheels when the grinding wheels are traversing workpiece surfaces in either direction.

It is also an object to provide an improved plural-surface grinding machine of this nature which incorporates automatic diamond dressing movement in the feed mechanism, the latter inherently compensating for this dressing movement when feeding the workpiece.

Other objects, features, and advantages of the present invention will become apparent from the subsequent description, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a typical workpiece tobe ground with the novel apparatus;

FIGURE 2 is a cross-sectional view taken along the line 22 of FIGURE 1 and further showing the workpiece configuration;

FIGURE 3 is a top plan view of the machine showing the radially arranged grinding wheel spindles;

FIGURE 4 is a cross-sectional view in elevation taken along thev line 4-4- of FIGURE 3, the grinding wheel spindles being omitted, showing the workpiece supporting shaft and its associated parts;

FIGURE 5 is a fragmentary elevational view taken in the direction of the arrow 5 of FIGURE 4 and showing the mounting of a diamond dresser and the key for retaining the dresser against rotational movement;

FIGURE 6 is a side elevational view of the mechanism for causing axial feed movement of the work supporting shaft as well as the fluid motor for oscillating the workpiece supporting shaft;

FIGURE 7 is a fragmentary cross-sectional view taken along the line 7-7 of FIGURE 6 and showing the eccentric feed shaft and its connection to the workpiece supporting shaft; 1

FIGURE 8 is a fragmentary cross-sectional view taken along the line 88 of FIGURE 6 and showing the means for supporting the dressing feed slide;

FIGURE 9 is a fragmentary cross-sectional view taken along the line 9-9 of FIGURE 6 and showing the dressing feed cylinder and its connection to the dressing feed screw, as well as the means for supporting the grinding feed slide;

FIGURE 10 is a side elevational view of one of the grinding wheel spindles;

FIGURE 11 is a top plan view of the grinding wheel spindle,'showing a portion of itsaxial feed actuating mechanism;

FIGURE 12 is a cross-sectional view taken along line 1212 of FIGURE 10 and showing the manner of sup- "ice '2 porting the grinding Wheel 'spindle slide, the spindle being removed; and

FIGURE 13 is a diagrammatic view showing the successive steps in the grinding operation.

In general terms, the illustrated embodiment of the invention comprises a workpiece supporting table mounted on a supporting shaft which is capable of both axial and oscillatory rotational movement. Means are provided for securing to the table a workpiece having a plurality of surfaces to be ground. Such aworkpiece may comprise an annular member having a plurality of circumferentially spaced apertures, each aperture being of elongated or oblong shape with parallel sides, the oscillation taking place parallel to these sides. I

A plurality of radially arranged grinding wheel spindles are provided, the spindles being movable radially inwardly so that the grinding wheels will pass through the apertures as the workpiece is. being oscillated. Diamond dressers are provided for the grinding wheels, these dressers being mounted outwardly of the corresponding workpiece apertures and being movable only axially with the workpiece supporting shaft and table.

Means are provided for axially feeding the oscillating table a predetermined dressing distance so that the wheels will be dressed as they pass the dressers (held against oscillation) when moving toward the workpiece apertures. As the dressed wheels approach the apertures, the workpiece will be retracted sufficiently to permit the Wheels to enter the apertures and overlap the first of each pair of surfaces. The work will then be axially shifted a predetermined grinding feed increment toward the wheels, this feed movement taking place, simultaneously with the traverse movement of the grinding wheels over the oscillating surfaces. When the grinding wheels finish their inward radial movement, one of each pair of parallel aperture surfaces will have been ground.

The means. for axially feeding the work supporting shaft comprises a double-lobed cam which follows a roller carried by a dressing feed slide. This slide is threadably connected to a dressing feed screw, the latter being in turn rotatably but non-slidably carried by a grinding feed slide in tandem relation with the dressing feed slide. The lobed cam is carried by an eccentric shaft connected to the workpiece supporting shaft. One lobe of the cam is urged against and follows the roller during the dressing feed and first grinding feed movements, the roller (and dressing feed slide) first being withdrawn by rotation of the dressing feed screw and then by movement of the grinding feed slide. After the grinding of the first aper ture sides is completed, the grinding feed slide is reversed, returning the cam, and thereforethe workpiece, to the position it had after the dressing feed movement but before the grinding feed movement.

The cam is then urged in the other direction, and is therefore swung so as to engage its other lobe, symmetrical with the first, with the roller. This has the effect of moving the second set of surfaces into grinding position, taking into account the previous dressing feed movement. The grinding wheel spindles will then be moved radially outwardly past the second of each pair of surfaces as the workpiece continues to oscillate. Simultaneously with this outward radial movement of the grinding wheels, the grinding feed slide will again be moved a pr edetermined grinding feed distance, the dressing feed increment having been already compensated for by the shifting movement of the cam to the other lobe.

After the grinding feed movement and the outward radial movement of the grinding wheel spindles have been completed, work oscillation will cease and the work may be detached from the table. The latter will support the next workpiece in a position which will compensate for the previous dressing feed, so that the pairs of surfaces will again be ground to the same spacing.

Referring more particularly to the drawings, the grinding machine is generally indicated at 21 and comprises a. frame 22 of generally rectangular shape, as seen in FIGURE 3, the frame having a central vertically extending bearing support retaining means 23, as seen in FIG- URE 4. A bearing support in the form of a sleeve 24 is secured within retaining means 23, and a guide sleeve 25 is rotatably supported therein by roller bearings 26 and 27 which hold sleeve 25 against axial movement. A workpiece supporting shaft 28 is non-rotatably mounted within sleeve 25, a key 29 being secured to the lower end of sleeve 25 and disposed within a keyway 31 formed within the lower end of shaft 28.

A workpiece supporting table 32 is secured by bolts 33 to the upper end of shaft 23, which extends a substantial distance above frame 22. Table 32 is of circular shape and is adapted to centrally support a workpiece generally indicated at 34.

The workpiece is seen in detail in FIGURES 1 and 2, it being understood that other types of workpieces could be ground with a machine incorporating the principles of this invention. Workpiece 34 is of annular shape, with a partly spherical outer surface 35 and a complementary inner surface. A plurality of slots or apertured portions generally indicated at 36 are disposed in circum ferentially spaced relation around member 34, extending through the workpiece. These apertures are of elongated or oblong shape, having arcuate ends 37 and straight sides 38 and 39 extending between the arcuate ends. The long axes of apertures 36 are shown as being in a common plane parallel to edges 38 and 39 and to the flat ends 41 and 42 of workpiece 34.

Such a workpiece may, for example, be a ball bearing retaining cage of a universal joint, and in ordinary practice it is necessary to machine, harden and then grind the critical workpiece surfaces. Grinding is not only required to remove unpredictable distortions resulting from residual thermal stresses, but is employed to obtain the final required size and surface finish. The machine of the present invention may be used to grind flat aperture surfaces 38 and 39 which are equidistantly spaced from the long aperture axis. The machine will simultaneously grind all surfaces 38 of the six apertures 36 shown in the illustrated workpiece, and will then simultaneously grind all surfaces 39.

Workpiece 34 may be mounted on table 32 with end 41 engaging the table, the workpiece surrounding a circular locating plate 43 centrally secured to table 32 as shown in FIGURE 4. A circular clamping plate 44 mounted on a rod 45 is engageable with upper end 42 of workpiece 34, rod 45 extending downwardly through plate 43, table 32 and a guide bushing 46 into a chamber 47 formed in the upper end of shaft 28. A piston 48 is secured to the lower end of rod 45, and fluid passageway means 49 is provided in shaft 23 for conducting pressure fluid to the upper end of chamber 47 in order to urge clamping plate 44 downwardly against the workpiece.

'FIGURE 4 also illustrates the location of a smaller workpiece 34 which may be secured by appropriate means to table 32 in place of workpiece 34, it being noted that the apertures 36 in workpiece 34 would be symmetrical about the same common plane as apertures 36.

Six grinding wheel spindle assemblies, each generally indicated at 51, are mounted on frame 2 2, as seen best in FIGURES 3, 10, 11 and 12. These spindle assemblies are radially arranged so as to permit the grinding wheels 52. carried thereby on horizontal axes to enter and be withdrawn from apertures 36. A guideway 53, seen partially in FIGURE 12, is provided on frame 22 for each spindle assembly SI, and each spindle assembly has a slide 54 movably mounted on guideway 53 and carrying a spindle support 55. A grinding wheel spindle 56; is rotatably 4 mounted in each spindle support and is driven by a motor 57 at the outer end thereof.

Means are provided for simultaneously shifting all six spindle assemblies 51 toward and away from the workpiece. This means includes a reciprocable fluid motor 58 comprising a cylinder pivotally secured at 59 to frame 22 and a piston rod 61 pivotally secured at 62 to a bellcrank 63. This bellcrank is one of six pivotally secured at 64 to frame 22 adjacent each spindle assembly 51. Each bellcrank 63 has a link 65 pivotally connecting it to its corresponding spindle assembly 51 so that rocking of the bellcrank will radially shift the spindle assenibly. All bellcrank are interconnected by additional links 66, so that movement of one bellcrank 63 by motor 53 Will simultaneously shift all the spindle assemblies.

A diamond dresser 67 is mounted adjacent each grinding wheel 52, the dresser being so disposed as to dress the wheel during movement of the latter from its retracted position, seen in solid lines in FIGURE 10, toward the workpiece. Each dresser 67 is secured to and extends upwardly from a bracket 68 secured to a dresser supporting table 69 by bolts 71. Table 69 is rotatably mounted by bearings '72 on shaft 28* between table 32 and the upper end of bearing support 24 A key 73 secured to table 69 is disposed within a slot 74 in a stationary member 75 on the upper end of bearing support 24, so as to prevent rotational movement of dressers 67. Bearings 72 prevent relative axial movement between table 69 and shaft 28 as seen in FIGURE 4, so that axial movement of the shaft will result in axial movement of dressers 67.

As will be noted in FIGURE 10', dressers 67 are spaced radially outwardly from surfaces 38 of apertures 36 a distance such that grinding wheels 52. will leave dressers 67 as they enter apertures 36 and engage surfaces 38, which then begin an upward grinding feed movement as later described. The fact that dressers 67 move upwardly with surfaces 38 during the first grinding feed movement will therefore not affect the surfaces of grinding wheels 52..

The means for oscillating workpiece 34 about the axis of shaft 28 during grinding comprises a rotary fluid motor 7 6, as seen in FIGURE 6. The vertical output shaft of this motor is connected by an eccentric shaft 77 to a connecting rod 78, this rod having a clevis 79 connected to a lever 81, which is secured to sleeve 25 and key member 29. When motor 76 is rotated, sleeve 25, shaft 23 and workpiece supporting table 3-2 will be oscillated through the desired arc, so that grinding wheels 52 grind surfaces 38 and 39, as later described.

The means for vertically feeding workpiece supporting shaft 28- comprises a feed shaft 82. rotatably mounted by bearings 33 and 84 within a bearing support 85 secured to frame 22. beneath shaft 23. A crank or eccentric portion 86, seen in FIGURE 7, is formed on one end of shaft 82 outwardly of bearing support 85 and immediately beneath shaft 28. The lower end 87 of shaft 28 is of reduced diameter, as seen in FIGURE 4, and an adaptor 88 is rotatably mounted by bearings 89 on shaft end 87, bearings 89 preventing relative axial movement between shaft end 87 and adaptor 88. The lower end 91 of adaptor '88 is connected by a pin 92 to the forked upper end 3 of a connecting member 94 rotatably mounted on eccentric portion 86 of shaft '82 by bearing 95, as seen in FIGURE 7.

In its central position, as seen in FIGURE 6, eccentric 86 is horizontally offset from the main portion of shaft 82, so that rocking of shaft -82 in either direction from its central position will cause vertical feeding movement of shaft 23. If shaft 82 is rocked counterclockwise, this feeding movement will be upward, and if shaft 82 is rocked clockwise, the feeding movement will be downward. A feed cam 96 is keyed to the outer end 37 of shaft 82. Cam 96 has two lobes 98 and 99 symmetrical about a plane containing the axis of shaft -82 and the crank arm of eccentric portion '86. Lobes 98 and 99 are of convex shape and have a recess 101 formed therebetween. A roller 1112 is engageable with cam 96 so as to control the feeding movement, as described below. Roller 102 is rotatably mounted at one end of a dressing feed slide 3, this'slide being supported for horizontal movement by a guideway 1114 secured'to frame 22, as seen in FIGURE 8.

A fluid motor 105 has its cylinder end pivotally secured at 1196 to a bracket 1117 carried by frame 22, and its piston rod 108 pivotally connected at 109 to cam 96. When piston rod 108 is urged to the left or to the right in FIGURE 6, horizontal movement of roller 102 in this figure will be accompanied by rotation of shaft 82, the direction'of this rotation depending upon the direction of movement of piston rod 1118 and of roller 1112. If cam 96 is urged counterclockwise from the FIGURE 6 position, lobe 98 will maintain engagement with roller 102, and shaft 28 will be shifted vertically upwardly when roller 1112 moves to the right and downwardly when roLler 1112 moves to the left. If cam 96 is urged clockwise from the FIGURE 6 position, lobe 99 will maintain engagement with roller 1112 and shaft 28 will move downwardly upon rightward movement of roller 102 and upwardly upon leftward movement of the roller.

A nut 111 is secured to the end of slide 163 opposite that which carries roller 102, and a dressing feed screw 112 is threadably mounted therein, as seen in FIGURE 6. Screw 112 has an unthreaded portion 113 rotatably and non-slidab ly mounted by bearings 114 within a minding feed slide 115, the latter being slidably mounted on guideway 104 in spaced relation with slide 1113. A ratchet 116 is keyed to shatit portion 113 of screw 112 adjacent a bearing support 117 provided on slide 115 for bearings 114.

A member 118 is rotatably mounted on the extended hub portion 119 of ratchet 116, and carries a pawl 121 by means of a pin 122, the pawl being urged by a spring 123 against ratchet 116. A fluid motor 124- has its cylinder end pivotally connected at 125 to a bracket 126 secured to and extending from frame 22, the piston rod 127 of motor 124 being pivotally connected at 128 to member 118, as seen in FIGURE 9. Pivot connection 125 is adjustable in the direction of the motor axis so as to preselect the length of stroke of motor 124. The arrangement is such that retracting movement of piston rod 127 will cause a predetermined rotation of screw 112 in a direction resulting in rightward movement of dressing slide 163, whereas extendingmo'vement of piston rod 127 will cause idle movement of pawl 121x The unthreaded portion 113 of screw 112 extends to the right in FIGURE 6 and has a hand whee-l 129-secured thereto for manual fee-d control. Pawl 1 21 is engageable with a projection 13% when piston rod 127 is fully extended, projection 130 freeing'pawl 121 from ratchet 116 to permit free rotation of screw 1112 by thehand wheel. The extended position of piston rod 127 is defined by a stop 131 engageable by member 118, as seen in FIG- URE 9.

A fluid motor 132 is provided for shifting slide 115 in either direction. The cylinder end of motor 132 is'connected at 133 to a bracket 134, pivotal *connection133 being adjustable in the direction of the motor axis to preseleot the retracted position of the motor. Piston rod 135 of motor 132 is connected by a-clevis 136 and a pin 137 to the upper end of a link 138, as seen in FIGURE 6, the lower end of this link being pivoted at 139 to stationary guide'way 104. A pair of parallel links 141 and 142, seen in FIGURE 9, are pivotally connected-at 143 to an intermediate portion of lever 138 and at 144 to slide 115. Reciprocating movement of motor 132 will thus result in horizontal movement of slides 115 and 103 connected by screw 112. An adjustable stationary stop 1 is provided for the right hand position of slide 115.

In describing the operation of unit 21, reference is made to the successive diagrammatic views in FIG URE 13. When the workpiece is in-its central position, as shown in FIGURES 6 and 10, the plane of symmetry of workpiece apertures 36 will pass through the centerlines of grinding wheel spindles 56; this plane is indicated at 1 16 in FIGURES 10 and 13.

However, the initial position of the parts will not be with workpiece apertures 36 centered on plane 146, but with the plane of symmetry of apertures '36- displaced a distance G from plane 146, as shown in FIGURE 13A. The distances G and G are the grinding feed distances (for surfaces 38 and 39 respectively which will achieve proper spacing of the finished surfaces 38 and 39.

In order to minimize errors during'a grinding operation, dressers 67 will be aligned with the desired finish position 38 of surface 33, and this is why the initial position of the workpiece will be with the displacement G since the dressers 67 can thus be advanced an additional distance D to dress wheels 52.

The initial position of workpiece 3-4 shown in FIGURE 13A will be achieved by pressurizing the head end of motor 132, thus engaging slide with adjustable stop 145. At the same time, the head end of motor 105 will be pressurized, so that cam 96 will be swung counterclockwise from its central position, shown in FIGURE 6, to its initial position in which lobe 98 will engage retracted roller 102. At this time, pawl motor 124 will be in its extended position as shown in FIGURE 9, with member 118 engaging stop 1311. Upon initiation of the cycle, motor 76 will be rotated so as to continuously oscillate workpiece 34 about the axis of shaft 28.

As grinding wheels 52 are moved radially inwardly toward dressers 6'7 by means of motor 53, the rod end of motor 124 will be pressurized, causing rotation of ratchet 116 and lead screw 112 in a direction which will retract roller 162 further to the right in FIGURE 6. Since the head end of motor 1115 continues to be pressurized, cam 96 will rotate a slight distance further counterclockwise, and workpiece 34 will be moved upwardly a dressing feed distance D this distance normally being substantially less than G Grinding wheels 52 will pass dressers 67, as seen in FIGURE 13B, and will be dressed thereby. After motor 124 has reached its fully retracted position, it will again be extended to move pawl 118 to the position of FIGURE 9.

The pressure in motor 132 will then be reversed, pressure being applied to the rod end, thus moving roller 1112 to the left in FIGURE 6. This will cause rocking of cam 96 against the pressure being applied in motor 165, and workpiece 34 will be withdrawn downwardly a distance G This will permit grinding wheels 52 to enter apertures 36, as seen'in FIGURE 13C.

After the leading edges of grinding wheels 52 have reached the inner edges of surfaces 38, the grinding wheels will continue their inward radial movement while pressure is again applied to the head end of motor 132. This will again retract roller 192, permitting counterclockwise movement of cam 96, and oscillating surfaces 38 will be fed upwardly against the grinding Wheels while the latter continue to move inwardly. This movement will continue until the position shown in FIGURE 131) is reached, at which time stop 145 will be engaged by slide115. Surfaces 38 will thus have been ground down to their finish size, indicated at 38'. The parts may remain in the position shown in FIGURE 1313 for a short time, until the oscillating surfaces 33' have been fully ground.

Motor 132 will then be retracted until it reaches t'n end of its stroke. This will cause clockwise movement of cam 96, returning workpiece 34 the distance G as shown in FIGURE 13E.

The pressure in motor 1115 will then be reversed and applied to the rod end. This will cause lobe 99 of cam 36 to engage roller 102, the cam rocking clockwise in FIGURE 6. Due to'the symmetrical nature of lobes 98 and 99, shaft 82 will be swung through an angular distance such that workpiece 34 will move downwardly twice the dressing distance D, as shown in FIGURE 13F.

Fluid will be reversed in motor 53, causing outward radial movement of grinding wheels 52. At the same time, fluid will again be applied to the head end of motor 132, causing roller 162 to be withdrawn from cam 96. Lobe 9 9 will maintain engagement with roller M2, and when slide 115 engages stop 145, the workpiece will have moved downwardly a distance G as shown in FIG- URE 13G. Surfaces 3? will thus have been ground to their finish size 39.

Grinding wheels 52 will continue to move radially outwardly, and rotation of motor 76 will be halted so that workpiece 34 may be removed.

Motor 105 will again be reversed, causing counterclockwise rotation of cam 96 in FIGURE 6. This will move workpiece supporting shaft 28 upwardly a distance equal to twice the grinding feed distance plus twice the dressing feed distance, as seen in FIGURE 13H. When a new workpiece 34a is mounted in the unit, it will thus be properly located so as to obtain the same spacing between surfaces Sfia and 3% after another dressing and grinding cycle.

While it will be apparent that the preferred embodiment of the invention disclosed is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. In a grinding machine for an annular workpiece having a plurality of circumferentially spaced apertured portions, means for continuously oscillating said workpiece about its axis, means for axially moving said workpiece in either direction from a central position during such oscillation, a plurality of circumferentially arranged grinding wheel spindles, and means for simultaneously moving said spindles toward or away from the workpiece axis, said means for axially moving the workpiece including means for moving the workpiece a predetermined distance from said central position to an initial grinding position upon movement of said spindles toward the workpiece axis and from said initial grinding position past said central position to a second initial grinding position equidistant to said first initial grinding position from said central position upon movement of said spindles away from the workpiece axis.

2. In a machine for grinding successive workpieces each of which has at least one pair of facing surfaces to be ground to a predetermined spacing, means for axially shifting said workpiece a predetermined initial distance from a central position to an initial grinding position, a grinding wheel spindle, means for moving said spindle toward or away from the workpiece, means for feeding said workpiece a predetermined first feed distance past said initial grinding position during spindle movement toward said workpiece and then returning said workpiece to said initial grinding position, means for further moving said workpiece past said central position to a second initial grinding position equidistant to said first initial grinding position from said central position, and means for axially moving said workpiece a second feed distance past said second initial grinding position during spindle movement away from said workpiece.

3. The combination according to claim 2, further provided with means for continuously oscillating said workpiece in the direction of extent of said surfaces comprising a workpiece supporting shaft and a reciprocable motor connected to said shaft, means for rotatably and slidably supporting said workpiece supporting shaft, said means for axially moving said workpiece comprising a crankshaft extending transversely to said workpiece sup-- porting shaft, and an operative connection between said crankshaft and one end of said workpiece supporting shaft, whereby rocking of said crankshaft will cause axial movement of said workpiece supporting shaft.

4. In a machine for grinding successive workpieces each of which has at least one pair of facing surfaces to be ground to a predetermined spacing, means for axially shifting said workpiece a predetermined initial distance from a central position to an initial grinding position, a grinding wheel spindle, means for moving said spindle toward or away from the workpiece, means for feeding said workpiece a predetermined first feed distance past said initial grinding position during spindle movement toward said workpiece and then returning said workpiece to said initial grinding position, means for further moving said workpiece past said central position to a second initial grind-ing position equidistant to said first initial grinding position from said central position, means for axially movng said workpiece a second feed distance past said second initial grinding position during spindle movement away from said workpiece, means for continuously oscillating said workpiece in the direction of extent of said surfaces comprising a workpiece supporting shaft and a reciprocable motor connected to said shaft, means for rotatably and slidably supporting said workpiece supporting shaft, said means for axially moving said workpiece comprising a crankshaft extending transversely to said workpiece support-ing shaft, an operative connection between said crankshaft and one end of said workpiece supporting shaft, whereby rocking of said crankshaft will cause axial movement of said workpiece supporting shaft, said means for shifting said workpiece to said first initial grinding position comprising .a cam fixed to said crankshaft and having a first lobe, a cam-engaging member engageable by said first lobe, a dressing feed slide supporting said cam-engaging member, a dressing feed screw threadably connected to said slide, and means for rotating said dressing feed screw.

5. The combination according to claim 4-, said means for feeding said workpiece said first feed distance and returning said workpiece to said first initial grinding position comprising a grinding feed slide rotatably and nonslidably supporting said dressing feed screw, and means for reciprocating said grinding feed slide.

6. The combination according to claim 5, said means for shifting said workpiece to said second initial grinding position comprising a second lobe on said cam symmetrical with said first lobe about a plane passing through said crankshaft axis and the crank arm of said crankshaft, and a reversible motor connected to said cam for withdrawing said first lobe from said cam-engaging member and causing said second lobe to engage said member.

7. In combination, a workpiece supporting shaft, a dresser support rotatably and nonslidably mounted on said shaft, means for continuously oscillating said workpiece supporting shaft on its axis, stationary means for holding said dresser support against rotation during said oscillating movement, means for imparting an axial feed movement to said workpiece supporting shaft, a grinding wheel spindle, and means for moving said spindle toward alilidftaway from the axis of said workpiece supporting s a 8. The combination according to claim 7, said means for imparting an axial feed movement to said workpiece supporting shaft comprising a dressing feed slide and a grinding feed slide in tandem relation, means connecting one of said slides to said workpiece supporting shaft and responsive to movement of said one slide in one direction to shift said workpiece supporting shaft axially in one direction, a feed screw threadably connected to said one slide, said feed screw being rotatably and nonslidably mounted in the other slide, means for rotating said feed screw, and means for shifting said other slide.

9. The combination according to claim 8, said connecting means between said one slide and said workpiece supporting shaft comprising a roller carried by said one slide,

an eccentric shaft rotatable on an axis extending transversely to the workpiece supporting shaft axis, a cam fixed to the concentric portion of said eccentric shaft and having a lobe engageable with said roller, a connection between the eccentric portion of said eccentric shaft and one end of said workpiece supporting shaft, and means constantly urging said cam against said roller.

10. In a machine for grinding successive workpieces each of which has at least one pair of facing surfaces to be ground to a predetermined spacing, a workpiece supporting member, means supporting said member for sliding movement, a dresser support nonslidably mounted on said member, a grinding wheel spindle, a stationary support for said spindle outwardly of said dresser support, means for shifting said spindle on its axis past said dresser support and toward or away from said workpiece supporting member, a crankshaft, an operative connection between the eccentric portion of said crankshaft and said workpiece supporting member, whereby rotation of said crankshaft in either direction will axially shift said workpiece supporting member in either direction, means for selectively urging said crankshaft in either direction of rotation, a cam fixed to the concentric portion of said crankshaft and having first and second lobes symmetrical about a plane, a dressing feed slide and a grinding feed slide, means supporting both of said slides in tandem relation, a cam engaging element carried by said dressing feed slide, a dressing feed screw threadably connected to said dressing feed slide, said dressing feed screw being rotatably and nonslidably mounted in said grinding feed slide, means for rotating said dressing feed screw, and means for shifting said grinding feed slide in either direction.

11. The combination according to claim 10, said means for rotating said dressing feed screw comprising a ratchet fixed to said screw, a pawl rockably mounted on the axis 19 of said screw, means for limiting movement of said pawl in one direction, said pawl being operatively engageable with said ratchet when moved in the opposite direction, and means for adjusting the extent of movement of said pawl in said opposite direction.

12. The combination according to claim 10, said means for shifting said grinding feed slide comprising a reciproc-able motor connected to said slide, and means for adjusting the stroke limits of said motor in both directions.

13. In a machine for grinding successive workpieces each of which has at least one pair of facing surfaces to be ground to a predetermined spacing, a workpiece supporting member, means supporting said member for sliding movement, a dresser support nonslidably mounted on said member, a grinding wheel spindle, a stationary support for said spindle outwardly of said dresser support, means for shifting said spindle on its axis past said dresser support and toward or away from said workpiece supporting member, a crankshaft, an operative connect-ion between the eccentric portion of said crankshaft and said workpiece supporting member, whereby rotation of said crankshaft in either direction will axially shift said workpiece supporting member in either direction, means for selectively urging said crankshaft in either direction of rotation, a cam fixed to the concentric portion of said crankshaft and having first and second lobes symmetrical about a plane, a cam engaging element disposed between said lobes, and means for selectively positioning said cam engaging element at various distances from the axis of said crankshaft.

Martin Aug. 21, 1906 Rzeppa Jan. 5, 1943 

1. IN A GRINDING MACHINE FOR AN ANNULAR WORKPIECE HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED APERTURED PORTIONS, MEANS FOR CONTINUOUSLY OSCILLATING SAID WORKPIECE ABOUT ITS AXIS, MEANS FOR AXIALLY MOVING SAID WORKPIECE IN EITHER DIRECTION FROM A CENTRAL POSITION DURING SUCH OSCILLATION, A PLURALITY OF CIRCUMFERENTIALLY ARRANGED GRINDING WHEEL SPINDLES, AND MEANS FOR SIMULTANEOUSLY MOVING SAID SPINDLES TOWARD OR AWAY FROM THE WORKPIECE AXIS, SAID MEANS FOR AXIALLY MOVING THE WORK- 